* Added undo/redo support to ConsoleWidget

* Fixed input_buffer being fetched incorrectly when the text buffer has been truncated by QPlainTextEdit

IPython/frontend/qt/console/console_widget.py

@@ -1,650 +1,668
 # Standard library imports
 import re
 
 # System library imports
 from PyQt4 import QtCore, QtGui
 
 # Local imports
 from completion_widget import CompletionWidget
 
 
 class AnsiCodeProcessor(object):
     """ Translates ANSI escape codes into readable attributes.
     """
 
     def __init__(self):
         self.ansi_colors = ( # Normal, Bright/Light
                              ('#000000', '#7f7f7f'), # 0: black
                              ('#cd0000', '#ff0000'), # 1: red
                              ('#00cd00', '#00ff00'), # 2: green
                              ('#cdcd00', '#ffff00'), # 3: yellow
                              ('#0000ee', '#0000ff'), # 4: blue
                              ('#cd00cd', '#ff00ff'), # 5: magenta
                              ('#00cdcd', '#00ffff'), # 6: cyan
                              ('#e5e5e5', '#ffffff')) # 7: white
         self.reset()
         
     def set_code(self, code):
         """ Set attributes based on code.
         """
         if code == 0:
             self.reset()
         elif code == 1:
             self.intensity = 1
             self.bold = True
         elif code == 3:
             self.italic = True
         elif code == 4:
             self.underline = True
         elif code == 22:
             self.intensity = 0
             self.bold = False
         elif code == 23:
             self.italic = False
         elif code == 24:
             self.underline = False
         elif code >= 30 and code <= 37:
             self.foreground_color = code - 30
         elif code == 39:
             self.foreground_color = None
         elif code >= 40 and code <= 47:
             self.background_color = code - 40
         elif code == 49:
             self.background_color = None
         
     def reset(self):
         """ Reset attributs to their default values.
         """
         self.intensity = 0
         self.italic = False
         self.bold = False
         self.underline = False
         self.foreground_color = None
         self.background_color = None
 
 
 class QtAnsiCodeProcessor(AnsiCodeProcessor):
     """ Translates ANSI escape codes into QTextCharFormats.
     """
     
     def get_format(self):
         """ Returns a QTextCharFormat that encodes the current style attributes.
         """
         format = QtGui.QTextCharFormat()
 
         # Set foreground color
         if self.foreground_color is not None:
             color = self.ansi_colors[self.foreground_color][self.intensity]
             format.setForeground(QtGui.QColor(color))
 
         # Set background color
         if self.background_color is not None:
             color = self.ansi_colors[self.background_color][self.intensity]
             format.setBackground(QtGui.QColor(color))
 
         # Set font weight/style options
         if self.bold:
             format.setFontWeight(QtGui.QFont.Bold)
         else:
             format.setFontWeight(QtGui.QFont.Normal)
         format.setFontItalic(self.italic)
         format.setFontUnderline(self.underline)
 
         return format
 
 
 class ConsoleWidget(QtGui.QPlainTextEdit):
     """ Base class for console-type widgets. This class is mainly concerned with
         dealing with the prompt, keeping the cursor inside the editing line, and
         handling ANSI escape sequences.
     """
 
     # Regex to match ANSI escape sequences
     _ansi_pattern = re.compile('\x01?\x1b\[(.*?)m\x02?')
     
     # When ctrl is pressed, map certain keys to other keys (without the ctrl):
     _ctrl_down_remap = { QtCore.Qt.Key_B : QtCore.Qt.Key_Left,
                          QtCore.Qt.Key_F : QtCore.Qt.Key_Right,
                          QtCore.Qt.Key_A : QtCore.Qt.Key_Home,
                          QtCore.Qt.Key_E : QtCore.Qt.Key_End,
                          QtCore.Qt.Key_P : QtCore.Qt.Key_Up,
                          QtCore.Qt.Key_N : QtCore.Qt.Key_Down,
                          QtCore.Qt.Key_D : QtCore.Qt.Key_Delete, }
 
     #---------------------------------------------------------------------------
     # 'QWidget' interface
     #---------------------------------------------------------------------------
 
     def __init__(self, parent=None):
         QtGui.QPlainTextEdit.__init__(self, parent)
 
         # Initialize public and protected variables
         self.ansi_codes = True
+        self.buffer_size = 500
         self.continuation_prompt = '> '
         self.gui_completion = True
         self._ansi_processor = QtAnsiCodeProcessor()
         self._completion_widget = CompletionWidget(self)
         self._executing = False
         self._prompt = ''
         self._prompt_pos = 0
         self._reading = False
         
-        # Configure some basic QPlainTextEdit settings
-        self.setLineWrapMode(QtGui.QPlainTextEdit.WidgetWidth)
-        self.setMaximumBlockCount(500) # Limit text buffer size
-        self.setUndoRedoEnabled(False)
-
         # Set a monospaced font
         point_size = QtGui.QApplication.font().pointSize()
         font = QtGui.QFont('Monospace', point_size)
         font.setStyleHint(QtGui.QFont.TypeWriter)
         self._completion_widget.setFont(font)
         self.document().setDefaultFont(font)
 
         # Define a custom context menu
         self._context_menu = QtGui.QMenu(self)
 
         copy_action = QtGui.QAction('Copy', self)
         copy_action.triggered.connect(self.copy)
         self.copyAvailable.connect(copy_action.setEnabled)
         self._context_menu.addAction(copy_action)
 
         self._paste_action = QtGui.QAction('Paste', self)
         self._paste_action.triggered.connect(self.paste)
         self._context_menu.addAction(self._paste_action)
         self._context_menu.addSeparator()
 
         select_all_action = QtGui.QAction('Select All', self)
         select_all_action.triggered.connect(self.selectAll)
         self._context_menu.addAction(select_all_action)
 
     def contextMenuEvent(self, event):
         """ Reimplemented to create a menu without destructive actions like
             'Cut' and 'Delete'.
         """
         clipboard_empty = QtGui.QApplication.clipboard().text().isEmpty()
         self._paste_action.setEnabled(not clipboard_empty)
         
         self._context_menu.exec_(event.globalPos())
 
     def keyPressEvent(self, event):
         """ Reimplemented to create a console-like interface.
         """
         intercepted = False
         cursor = self.textCursor()
         position = cursor.position()
         key = event.key()
         ctrl_down = event.modifiers() & QtCore.Qt.ControlModifier
         alt_down = event.modifiers() & QtCore.Qt.AltModifier
         shift_down = event.modifiers() & QtCore.Qt.ShiftModifier
 
-        if ctrl_down:
+        # Even though we have reimplemented 'paste', the C++ level slot is still
+        # called by Qt. So we intercept the key press here.
+        if event.matches(QtGui.QKeySequence.Paste):
+            self.paste()
+            intercepted = True
+
+        elif ctrl_down:
             if key in self._ctrl_down_remap:
                 ctrl_down = False
                 key = self._ctrl_down_remap[key]
                 event = QtGui.QKeyEvent(QtCore.QEvent.KeyPress, key, 
                                         QtCore.Qt.NoModifier)
 
             elif key == QtCore.Qt.Key_K:
                 if self._in_buffer(position):
                     cursor.movePosition(QtGui.QTextCursor.EndOfLine,
                                         QtGui.QTextCursor.KeepAnchor)
                     cursor.removeSelectedText()
                 intercepted = True
 
             elif key == QtCore.Qt.Key_Y:
                 self.paste()
                 intercepted = True
 
         elif alt_down:
             if key == QtCore.Qt.Key_B:
                 self.setTextCursor(self._get_word_start_cursor(position))
                 intercepted = True
                 
             elif key == QtCore.Qt.Key_F:
                 self.setTextCursor(self._get_word_end_cursor(position))
                 intercepted = True
 
             elif key == QtCore.Qt.Key_Backspace:
                 cursor = self._get_word_start_cursor(position)
                 cursor.setPosition(position, QtGui.QTextCursor.KeepAnchor)
                 cursor.removeSelectedText()
                 intercepted = True
 
             elif key == QtCore.Qt.Key_D:
                 cursor = self._get_word_end_cursor(position)
                 cursor.setPosition(position, QtGui.QTextCursor.KeepAnchor)
                 cursor.removeSelectedText()
                 intercepted = True
 
         if self._completion_widget.isVisible():
             self._completion_widget.keyPressEvent(event)
             intercepted = event.isAccepted()
         
         else:
             if key in (QtCore.Qt.Key_Return, QtCore.Qt.Key_Enter):
                 if self._reading:
                     self._reading = False
                 elif not self._executing:
-                    self._executing = True
                     self.execute(interactive=True)
                 intercepted = True
 
             elif key == QtCore.Qt.Key_Up:
                 if self._reading or not self._up_pressed():
                     intercepted = True
                 else:
                     prompt_line = self._get_prompt_cursor().blockNumber()
                     intercepted = cursor.blockNumber() <= prompt_line
 
             elif key == QtCore.Qt.Key_Down:
                 if self._reading or not self._down_pressed():
                     intercepted = True
                 else:
                     end_line = self._get_end_cursor().blockNumber()
                     intercepted = cursor.blockNumber() == end_line
 
             elif key == QtCore.Qt.Key_Tab:
                 if self._reading:
                     intercepted = False
                 else:
                     intercepted = not self._tab_pressed()
 
             elif key == QtCore.Qt.Key_Left:
                 intercepted = not self._in_buffer(position - 1)
 
             elif key == QtCore.Qt.Key_Home:
                 cursor.movePosition(QtGui.QTextCursor.StartOfLine)
                 start_pos = cursor.position()
                 start_line = cursor.blockNumber()
                 if start_line == self._get_prompt_cursor().blockNumber():
                     start_pos += len(self._prompt)
                 else:
                     start_pos += len(self.continuation_prompt)
                 if shift_down and self._in_buffer(position):
                     self._set_selection(position, start_pos)
                 else:
                     self._set_position(start_pos)
                 intercepted = True
 
             elif key == QtCore.Qt.Key_Backspace and not alt_down:
 
                 # Line deletion (remove continuation prompt)
                 len_prompt = len(self.continuation_prompt)
                 if cursor.columnNumber() == len_prompt and \
                         position != self._prompt_pos:
                     cursor.setPosition(position - len_prompt, 
                                        QtGui.QTextCursor.KeepAnchor)
                     cursor.removeSelectedText()
 
                 # Regular backwards deletion
                 else:
                     anchor = cursor.anchor()
                     if anchor == position:
                         intercepted = not self._in_buffer(position - 1)
                     else:
                         intercepted = not self._in_buffer(min(anchor, position))
 
             elif key == QtCore.Qt.Key_Delete:
                 anchor = cursor.anchor()
                 intercepted = not self._in_buffer(min(anchor, position))
 
         # Don't move cursor if control is down to allow copy-paste using
-        # the keyboard in any part of the buffer
+        # the keyboard in any part of the buffer.
         if not ctrl_down:
             self._keep_cursor_in_buffer()
 
         if not intercepted:
             QtGui.QPlainTextEdit.keyPressEvent(self, event)
 
     #--------------------------------------------------------------------------
     # 'QPlainTextEdit' interface
     #--------------------------------------------------------------------------
 
     def appendPlainText(self, text):
         """ Reimplemented to not append text as a new paragraph, which doesn't
             make sense for a console widget. Also, if enabled, handle ANSI
             codes.
         """
         cursor = self.textCursor()
         cursor.movePosition(QtGui.QTextCursor.End)
 
         if self.ansi_codes:
             format = QtGui.QTextCharFormat()
             previous_end = 0
             for match in self._ansi_pattern.finditer(text):
                 cursor.insertText(text[previous_end:match.start()], format)
                 previous_end = match.end()
                 for code in match.group(1).split(';'):
                     self._ansi_processor.set_code(int(code))
                 format = self._ansi_processor.get_format()
             cursor.insertText(text[previous_end:], format)
         else:
             cursor.insertText(text)
 
     def paste(self):
         """ Reimplemented to ensure that text is pasted in the editing region.
         """
         self._keep_cursor_in_buffer()
         QtGui.QPlainTextEdit.paste(self)
 
     #---------------------------------------------------------------------------
     # 'ConsoleWidget' public interface
     #---------------------------------------------------------------------------
 
     def execute(self, interactive=False):
         """ Execute the text in the input buffer. Returns whether the input
             buffer was completely processed and a new prompt created.
         """
         self.appendPlainText('\n')
+        self._executing_input_buffer = self.input_buffer
+        self._executing = True
         self._prompt_finished()
         return self._execute(interactive=interactive)
 
     def _get_input_buffer(self):
+        # If we're executing, the input buffer may not even exist anymore due
+        # the limit imposed by 'buffer_size'. Therefore, we store it.
+        if self._executing:
+            return self._executing_input_buffer
+
         cursor = self._get_end_cursor()
         cursor.setPosition(self._prompt_pos, QtGui.QTextCursor.KeepAnchor)
 
         # Use QTextDocumentFragment intermediate object because it strips
         # out the Unicode line break characters that Qt insists on inserting.
         input_buffer = str(cursor.selection().toPlainText())
 
         # Strip out continuation prompts
         return input_buffer.replace('\n' + self.continuation_prompt, '\n')
 
     def _set_input_buffer(self, string):
         # Add continuation prompts where necessary
         lines = string.splitlines()
         for i in xrange(1, len(lines)):
             lines[i] = self.continuation_prompt + lines[i]
         string = '\n'.join(lines)
 
         # Replace buffer with new text
         cursor = self._get_end_cursor()
         cursor.setPosition(self._prompt_pos, QtGui.QTextCursor.KeepAnchor)
         cursor.insertText(string)
         self.moveCursor(QtGui.QTextCursor.End)
 
     input_buffer = property(_get_input_buffer, _set_input_buffer)
 
     def _get_input_buffer_cursor_line(self):
+        if self._executing:
+            return None
         cursor = self.textCursor()
         if cursor.position() >= self._prompt_pos:
             text = str(cursor.block().text())
             if cursor.blockNumber() == self._get_prompt_cursor().blockNumber():
                 return text[len(self._prompt):]
             else:
                 return text[len(self.continuation_prompt):]
         else:
             return None
 
     input_buffer_cursor_line = property(_get_input_buffer_cursor_line)
 
     #---------------------------------------------------------------------------
     # 'ConsoleWidget' abstract interface
     #---------------------------------------------------------------------------
 
     def _execute(self, interactive):
         """ Called to execute the input buffer. When triggered by an the enter
             key press, 'interactive' is True; otherwise, it is False. Returns
             whether the input buffer was completely processed and a new prompt
             created.
         """
         raise NotImplementedError
 
     def _prompt_started_hook(self):
         """ Called immediately after a new prompt is displayed.
         """
         pass
 
     def _prompt_finished_hook(self):
         """ Called immediately after a prompt is finished, i.e. when some input
             will be processed and a new prompt displayed.
         """
         pass
 
     def _up_pressed(self):
         """ Called when the up key is pressed. Returns whether to continue
             processing the event.
         """
         return True
 
     def _down_pressed(self):
         """ Called when the down key is pressed. Returns whether to continue
             processing the event.
         """
         return True
 
     def _tab_pressed(self):
         """ Called when the tab key is pressed. Returns whether to continue
             processing the event.
         """
         return False
 
     #--------------------------------------------------------------------------
     # 'ConsoleWidget' protected interface
     #--------------------------------------------------------------------------
 
     def _complete_with_items(self, cursor, items):
         """ Performs completion with 'items' at the specified cursor location.
         """
         if len(items) == 1:
             cursor.setPosition(self.textCursor().position(), 
                                QtGui.QTextCursor.KeepAnchor)
             cursor.insertText(items[0])
         elif len(items) > 1:
             if self.gui_completion:
                 self._completion_widget.show_items(cursor, items) 
             else:
                 text = '\n'.join(items) + '\n'
                 self._write_text_keeping_prompt(text)
                 
     def _get_end_cursor(self):
         """ Convenience method that returns a cursor for the last character.
         """
         cursor = self.textCursor()
         cursor.movePosition(QtGui.QTextCursor.End)
         return cursor
 
     def _get_prompt_cursor(self):
         """ Convenience method that returns a cursor for the prompt position.
         """
         cursor = self.textCursor()
         cursor.setPosition(self._prompt_pos)
         return cursor
 
     def _get_selection_cursor(self, start, end):
         """ Convenience method that returns a cursor with text selected between
             the positions 'start' and 'end'.
         """
         cursor = self.textCursor()
         cursor.setPosition(start)
         cursor.setPosition(end, QtGui.QTextCursor.KeepAnchor)
         return cursor
 
     def _get_word_start_cursor(self, position):
         """ Find the start of the word to the left the given position. If a
             sequence of non-word characters precedes the first word, skip over
             them. (This emulates the behavior of bash, emacs, etc.)
         """
         document = self.document()
         position -= 1
         while self._in_buffer(position) and \
                 not document.characterAt(position).isLetterOrNumber():
             position -= 1
         while self._in_buffer(position) and \
                 document.characterAt(position).isLetterOrNumber():
             position -= 1
         cursor = self.textCursor()
         cursor.setPosition(position + 1)
         return cursor
 
     def _get_word_end_cursor(self, position):
         """ Find the end of the word to the right the given position. If a
             sequence of non-word characters precedes the first word, skip over
             them. (This emulates the behavior of bash, emacs, etc.)
         """
         document = self.document()
         end = self._get_end_cursor().position()
         while position < end and \
                 not document.characterAt(position).isLetterOrNumber():
             position += 1
         while position < end and \
                 document.characterAt(position).isLetterOrNumber():
             position += 1
         cursor = self.textCursor()
         cursor.setPosition(position)
         return cursor
 
     def _prompt_started(self):
         """ Called immediately after a new prompt is displayed.
         """
+        # Temporarily disable the maximum block count to permit undo/redo.
+        self.setMaximumBlockCount(0)
+        self.setUndoRedoEnabled(True)
+
+        self.setReadOnly(False)
         self.moveCursor(QtGui.QTextCursor.End)
         self.centerCursor()
-        self.setReadOnly(False)
+
         self._executing = False
         self._prompt_started_hook()
 
     def _prompt_finished(self):
         """ Called immediately after a prompt is finished, i.e. when some input
             will be processed and a new prompt displayed.
         """
+        # This has the (desired) side effect of disabling the undo/redo history.
+        self.setMaximumBlockCount(self.buffer_size)
+
         self.setReadOnly(True)
         self._prompt_finished_hook()
 
     def _set_position(self, position):
         """ Convenience method to set the position of the cursor.
         """
         cursor = self.textCursor()
         cursor.setPosition(position)
         self.setTextCursor(cursor)
 
     def _set_selection(self, start, end):
         """ Convenience method to set the current selected text.
         """
         self.setTextCursor(self._get_selection_cursor(start, end))
 
     def _show_prompt(self, prompt):
         """ Writes a new prompt at the end of the buffer.
         """
         self.appendPlainText('\n' + prompt)
         self._prompt = prompt
         self._prompt_pos = self._get_end_cursor().position()
         self._prompt_started()
 
     def _show_continuation_prompt(self):
         """ Writes a new continuation prompt at the end of the buffer.
         """
         self.appendPlainText(self.continuation_prompt)
         self._prompt_started()
 
     def _write_text_keeping_prompt(self, text):
         """ Writes 'text' after the current prompt, then restores the old prompt
             with its old input buffer.
         """
         input_buffer = self.input_buffer
         self.appendPlainText('\n')
         self._prompt_finished()
 
         self.appendPlainText(text)
         self._show_prompt(self._prompt)
         self.input_buffer = input_buffer
 
     def _in_buffer(self, position):
         """ Returns whether the given position is inside the editing region.
         """
         return position >= self._prompt_pos
 
     def _keep_cursor_in_buffer(self):
         """ Ensures that the cursor is inside the editing region. Returns
             whether the cursor was moved.
         """
         cursor = self.textCursor()
         if cursor.position() < self._prompt_pos:
             cursor.movePosition(QtGui.QTextCursor.End)
             self.setTextCursor(cursor)
             return True
         else:
             return False
 
 
 class HistoryConsoleWidget(ConsoleWidget):
     """ A ConsoleWidget that keeps a history of the commands that have been
         executed.
     """
     
     #---------------------------------------------------------------------------
     # 'QWidget' interface
     #---------------------------------------------------------------------------
 
     def __init__(self, parent=None):
         super(HistoryConsoleWidget, self).__init__(parent)
 
         self._history = []
         self._history_index = 0
 
     #---------------------------------------------------------------------------
     # 'ConsoleWidget' public interface
     #---------------------------------------------------------------------------
 
     def execute(self, interactive=False):
         """ Reimplemented to the store history.
         """
         stripped = self.input_buffer.rstrip()
         executed = super(HistoryConsoleWidget, self).execute(interactive)
         if executed:
             self._history.append(stripped)
             self._history_index = len(self._history)
         return executed
 
     #---------------------------------------------------------------------------
     # 'ConsoleWidget' abstract interface
     #---------------------------------------------------------------------------
 
     def _up_pressed(self):
         """ Called when the up key is pressed. Returns whether to continue
             processing the event.
         """
         prompt_cursor = self._get_prompt_cursor()
         if self.textCursor().blockNumber() == prompt_cursor.blockNumber():
             self.history_previous()
 
             # Go to the first line of prompt for seemless history scrolling.
             cursor = self._get_prompt_cursor()
             cursor.movePosition(QtGui.QTextCursor.EndOfLine)
             self.setTextCursor(cursor)
 
             return False
         return True
 
     def _down_pressed(self):
         """ Called when the down key is pressed. Returns whether to continue
             processing the event.
         """
         end_cursor = self._get_end_cursor()
         if self.textCursor().blockNumber() == end_cursor.blockNumber():
             self.history_next()
             return False
         return True
 
     #---------------------------------------------------------------------------
     # 'HistoryConsoleWidget' interface
     #---------------------------------------------------------------------------
 
     def history_previous(self):
         """ If possible, set the input buffer to the previous item in the
             history.
         """
         if self._history_index > 0:
             self._history_index -= 1
             self.input_buffer = self._history[self._history_index]
 
     def history_next(self):
         """ Set the input buffer to the next item in the history, or a blank
             line if there is no subsequent item.
         """
         if self._history_index < len(self._history):
             self._history_index += 1
             if self._history_index < len(self._history):
                 self.input_buffer = self._history[self._history_index]
             else:
                 self.input_buffer = ''